There are many systems which are utilized for the detection of chemical warfare agents, some systems of which depend upon the impingement of liquid droplets against a detection surface for the measurement of the amount of chemical agent present in the environment. All such systems have a need for periodic testing of efficiency or effectiveness during their storage life. As a result of these requirements, the testing of the various systems is accomplished with the agents themselves. However, many of the agents are non-newtonian liquids which during droplet formation tend to have stringers or tend to form irregular size micro-drops, and these can cause inaccurate readings relative to the quantitative measurements.
The generation of discrete stringerless drops for the aforesaid test is extremely difficult when using high-viscosity, non-newtonian liquids. These liquids tend to form ligaments or stringers in the formation of the droplet. The ligaments tend to cause the drop to change its direction of flight, and sometimes are accompanies by unwanted droplets of a satellite nature. The complexity of the operation is further enlarged by the elastic properties and surface tension of the non-newtonian liquids when attempting to form microsize drops having diameters of less than about 1 mm. Many liquid-drop generators of the art have been evaluated with very limited success using high viscosity, non-newtonian liquids.
The art has provided the following devices for the production of liquid-droplets, viz: a spinning disc, a vibrating reed, a vibrating orifice, and air spray nozzle, and a pendant liquid-drop generator. However, all of the droplets produced by the foregoing art using highly viscous, non-newtonian fluids had stringers.
What is needed in the art is a liquid-drop generator for use in producing a liquid-drop from a high viscous non-newtonian fluid, on a reproducable basis, having a diameter between 0.5 and 5.0 mm of consistent geometry without stringers or ligaments.